I have been looking into and studying electric propulsion for about five years now and have pretty much relinquished to the fact that it will be a long time before we have the endurance, speed, and battery life I would desire on my Tandem Island when electric propulsion is used for primary propulsion only. At least at the speeds that I like to travel, 2-3 mph simply doesn't cut it for me, my normal preferred cruising speed is 8-10 mph. I have had quite a bit of success however using supplimental power (currently hybrid gas) to provide a small portion of my power needs, with the remainder of my propulsive power coming from my sails and pedal drives ( I've actually had quite a bit of success at utilizing tri-power propulsion (ie... sail, pedal, and supplemental power (gas or electric)) . I really like the Torqeedo 403 and that motor would be indeed my preferred platform to work with for all kinds of reasons, but unfortunately the TI is a little too large for such a small motor. So on my TI my choices would be either twin 403's or a single 1003 Torqeedo (maybe twin 1003's as well). What I am thinking is with twin 403's mounted on the stern of the boat (one on each side of the rudder) would hopefully provide enough supplimental power to propel my TI to my required 8-10 mph cruising speeds in no to very light winds (of course with special custom high pitch propellers), utilizing tri-power. However I'm thinking this solution would be much more costly vs a single 1003 motor, given that I would need to buy two of everything. I have several questions: Since the motors will not ever be used for primary propulsion, I have no need for the stock propellers, I would need props with their power range from 8-12 mph (instead of 0-5 mph), has anyone tried different pitch props on either the 403 or the 1003. Specifically 12 inch pitch props.
Since the motor(s) will be in the water has anyone tried to re-generate electric power back into the batteries from your forward motion, when not providing propulsion (would be a really nice feature on a sailboat).
I'm pretty certain twin 403's or a single 1003 would provide all my power requirements (my current twin 2.3hp Honda's pumping out about 1/4 horse ea (just above idle) easily propel the boat with no sails or pedaling to 6 mph with my custom super high pitch props. At 1/4 throttle (around 3/4 hp ea power consumption) the current twin hybrid gas motors propel the boat to 8 mph with no sails out and no pedaling in calm water. I very seldom use the motors at wide open throttle ( WOT), yea it's really fast but the fuel economy is horrible (plus the motors are loud at WOT), my boat is simply not designed for that (only in dire emergencies).
I'm assuming I would mount a throttle control on each side of the boat if I go with the twin 403's, so I can vary one throttle or the other to help control trim.
Since I already have the twin 2.3 hp outboards, I will likely just keep them on the boat tilted up when using the electric propulsion. This is why the twin 403's is still a contender.
I'm thinking with my minimal horsepower requirements, I'm pretty certain I could propel the boat mostly on solar power with one solar panel on each tramp (one for each motor if I go with the 403's), or two panels one charging an extra 1003 battery and the other providing propulsion power along with the primary battery if I go with a single 1003 setup, and one set of batteries (one for each motor if the 403 setup is selected). I have determined I only need to provide around 1/4 hp from each motor (I think around 75-100 watts is all I need) since this is only supplemental propulsion (not primary propulsion). Since the solar system is rated at around 50 watts, conceivably I could easily achieve more than 10 hrs worth of propulsion on one set of batteries (sunshine is not a problem here in Florida lol). Ten hrs at 10mph is over 100 miles range.
Another viable option would be twin 1003 motors with super high pitch props and retire my hybrid outboards. With 12 inch pitch props I think I could pull it off. I would have a solar panel on each tramp (one for each motor). Which might duplicate my current system speed and powerwise ( I currently get around 60-100 mpg, so I can normally go out sailing all day typically for around $.50 to $.75 cents worth of gas at average speeds between 8 and 10 mph in no to very light winds, of course if the wind picks up so does my fuel economy. If the wind picks up above 10-12 mph I can just tilt the outboards up if I want, but I seldom do, (I just go way faster instead lol).
Personally I feel there is a major flaw in the entire trolling motor and small outboard industry's thinking whereas every single design out there is intended for primary propulsion for a 3000 lb fishing boat at a couple mph (trolling), or primary propulsion only on an inflatable zodiac or john boat to about 5 mph, so every manufacturer, every motor out there on the market is not pitched properly for our types of boats, and there are literally no aftermarket propellers made by anyone anywhere to suite our needs with Hobie pedal drive boats with sails. Think about it we are completely covered with our pedal drives anywhere from zero to 6 mph by our mirage drives and sail kits (our primary propulsion). We only need supplemental propulsion if we want to go faster, our optimum power range needs to be 6-10 mph, on a very light boat (usually less than 200 lbs). There is literally nothing out there on the market that covers this.
Another problem I have is all this stuff is still extremely expensive, pretty hard to justify a $5000 to $6000 dollar plus system that only has 1/8 to 1/4 of the performance and range of my current system (I currently have a 200 mile plus cruise range at 8-10 mph with 2-3 gallons of gas on board ($5-$6 bucks in fuel)). which with everything cost me around $2,000 bucks (that's with top of the line Honda engines (which are near double the price of everything else out there)).
Hopefully people can publish their power usage and range results, so I can get a better feel about actual power consumption vs what is published on Torqeedo's web site. I would hate to spend all that money, and find out I really only have 20 minutes worth of power before everything goes dark. The world is what it is. Bob
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